In the final section of a paper machine or a corresponding machine which produces a continuous paper or fibrous web, the paper web passed from the preceding sections is accumulated into a machine reel in the reel-up. Such a reel is formed around a reel spool, which is loaded against a reeling cylinder by means of which the paper web is guided onto the reel. At least the reeling cylinder is driven, wherein it can simultaneously rotate a freely rotating reel, or the reel can be center-driven, i.e., the reel spool is driven during the reeling.
In a normal work cycle of a continuous reeling of a paper web, the reel is changed by cutting the paper web and arranging its end around a new, empty reel spool, the old full reel is removed from the reel-up and transferred to further processing, and the paper web is reeled around the new reel spool into a full-size machine reel. This process is repeated as often as necessary.
One factor that affects the quality of the thus-produced machine reel is the force which is used to load the reel against the reeling cylinder during the reeling process, and during the loading this force is changed on the basis of certain parameters or by using a suitable program. The loading force is produced by means of a force device, typically a hydraulic cylinder, coupled to the reel spool via a suitable mechanism. This hydraulic cylinder can be coupled for example to pivotal arms connected pivotally to the frame of the reel-up. This coupling method is described for example in Finnish Patent Nos. 71107 and 98506 and in U.S. Pat. No. 5,251,835, in all of which the reel spool is at the same time supported by horizontal reeling rails. For example, in U.S. Pat. No. 5,251,835, the full reel is transferred along the reeling rails into a discharge position, and a new reel spool is simultaneously brought onto the reeling rails.
In U.S. Pat. No. 5,285,979, the load is effected by means of a carriage which moves in the frame of a reel-up along linear guides, to which carriage a loading hydraulic cylinder is coupled. The reel spool is arranged on a pivotal arm connected pivotally to the carriage. The arm is used only when removing the full reel by turning the pivotal arms into the unloading direction with special unloading cylinders.
In all the above-described known reel-ups, the aforementioned force device is used to take care of both the desired loading force and the transfer of the reel spool further from the reeling cylinder when the size of the reel is increased.
The aforementioned solutions require a substantial motion length of the force device effecting the motion and the force. The actual loading force is affected by a number of factors, such as the friction produced by the motion of the force device, and in addition to that the dynamic friction of the structure supporting the reel spool, during the movement of the reel spool.
European Patent No. 0 604 558, corresponding to U.S. Pat. No. 5,393,008, describes carriages arranged to move linearly on guides disposed parallel to the reeling rails, the position of the carriages being determined by means of hydraulic cylinders coupled between the frame of the reel-up and the carriages. The carriages are provided with press devices, which press the bearing housings located at the ends of the reel spool and resting on the reeling rails, towards the reeling cylinder by an adjustable force. On the other side of the bearing housing, the carriages are also provided with positioning devices by means of which it is possible to adjust the position of the reel spool in the carriages more precisely.